Receipts may contain bisphenol A and S, chemicals that a new study shows can alter brain development.

Pregnant women are being warned to avoid reaching for credit card and cash register receipts as the ubiquitous bits of paper are increasingly seen as a threat to unborn children.

The receipts can contain the toxin bisphenol A and its chemical cousin bisphenol S, chemicals that a new study shows can alter brain development and behaviour in animals exposed to extremely low doses.

The research published Monday by a team at the University of Calgary was done on zebrafish. But the findings are so worrying lead researcher Deborah Kurrasch and her colleagues are calling for “removal of all bisphenols from consumer merchandise.”

They also “suggest that pregnant mothers limit exposure to plastics and receipts ” — a recommendation that is being echoed by other researchers familiar with the power of the endocrine-disrupting chemicals.

The greatest risk is in the second trimester when infant brains are rapidly growing and would be most vulnerable to the ill effects of bisphenol A, or BPA, and Bisphenol S, BPS, which has been widely used to replace BPA.

The chemicals can have “real and measurable effects on brain development and behaviour,” the researchers report in the Proceedings of the National Academy of Sciences. Their experiments on embryonic fish found minuscule doses of the chemicals — far below levels deemed safe in Canada — stimulate excess growth of neural cells associated with hyperactivity.

BPA is used to harden plastic and is found in plastic containers, the lining of cans, and on the thermal paper that is used to produce everything from credit card receipts to theatre tickets. As concern about BPA has grown, it is increasingly being replaced by BPS which the study says is just as bad.

It “equally affects neurodevelopment,” says the study, that adds to mounting concerns about the chemicals that can leach into food and rub off receipts. Health Canada surveys have shown that 95 per cent of Canadians have trace amount of BPA in their urine, with the highest levels seen in children.

BPA are endocrine disrupters that have been linked to obesity, cancer and childhood neurological disorders such as anxiety and hyperactivity. Previous studies suggesting that BPA may affect brain development prompted Canada and some other countries to ban the chemical’s use in baby bottles and phase out its use in baby food containers.

Kurrasch and her colleagues say regulators need to go much further.

Their work on embryonic zebrafish found very low doses – “1,000 fold lower than the accepted human daily exposure” of BPA – lead to overproduction of neural cells in the hypothalamus, a region of the brain involved in hyperactivity.

“What we show is that BPA affects the timing of when neurons are born, and that presumably alters circuitry in the brain, so you get this slightly different wiring,” Kurrasch said in an interview. She is a developmental neuroscientist who studies how changes in the brain in early life can impact later life.

The team first exposed the fish to an extremely low dose of BPAcomparable to a level that has been measured in the Oldman River, which provides drinking water to the city of Lethbridge, Alta.

Kurrasch says she didn’t expect to see an effect at such a low dose, but embryos exposed for less than a day hatched into larvae that were much more active swimmers than normal zebrafish.

“I was very surprised,” Kurrasch says.

While fish are not humans, she says the way neurons form early in life is very similar “whether you are fish, or a mouse or a human.”

“The same series of steps lead to brain development,” she said.

While humans aren’t swimming in water contaminated with BPA and BPS, she says people “are exposed to these chemicals every day in terms of things we touch and foods we consume.”

And the doses the team linked with neural effects in the zebrafish were much lower than levels that have been measured in women’s placentas and serum taken from fetuses.

She is also concerned that manufacturers have turned to BPS with “little proper toxicology” as an alternative when producing the “BPA-free” products.

Given the findings that BPA and BPS are both harmful, the researchers say “a societal push to remove all bisphenols from our consumer goods is justified.”

Other researchers share their concern.

“That BPA and BPS produce similar effects is not surprising given their structural similarity but dismaying given how prevalent BPS has become in consumer products”, says Heather Patisaul at North Carolina State University, who was not involved with the study. Patisaul also researches how brain circuits arise and says the Calgary research makes “significant contributions to our understanding of how developmental BPA exposure may impact neural organization and behaviour.”

Like Kurrasch, Patisaul says people need to be aware that “BPA-free” does not mean “chemical-free” or “endocrine disrupter-free” and that products without BPA may have other hormonally active components.

“In terms of a ‘ban,’ I leave those decisions up to the regulators but there is certainly an overwhelming abundance of data suggesting that BPA and BPS are potentially harmful to humans,” says Patisual. She agrees individuals, including pregnant women, who want to limit exposure to BPA, BPS, and chemicals with similar properties should limit contact with receipts and plastics, particularly food and beverage containers.

Dr. Bruce Lanphear, at Simon Fraser University in B.C., said by email the Calgary study is consistent with earlier work indicating that BPA appears to impact brain development.

“I was already convinced the BPA was highly likely to be toxic and unnecessary,” said Lanphear, who is leading a study examining fetal and early childhood exposures to environmental neurotoxins.

“I do think that pregnant women should avoid exposure to BPA and other unnecessary environmental chemicals,” Lanpear said.

Health Canada was asked for comment on the new study but did not respond before deadline.

Twitter.com/margaretmunro

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‘Just say no thank you to receipts’

Within seconds of touching a credit card receipt bisphenol A can be absorbed by the skin. Greasy fingers – from say a French fry as you walk away from the cash register – can increase absorption.

And hand sanitizers, which the author of one recent U.S. study likened to “skin penetration enhancers,” may make it even worse.

“Just say no thank you to receipts” is researcher Deborah Kurrasch’s advice to consumers and pregnant women, whose babies might be at highest risk.

“If I were pregnant I probably wouldn’t take receipts, I’d probably be very careful about plastics and use as much glass as I possibly could,” says the University of Calgary researcher. She is also a mother of eight- and 10-year-olds who does not want to freak mothers out, but does want to educate them.

She says the problem with receipts is that they are often printed on thermal paper that can be coated with BPA, a known endocrine disrupter that has been associated with childhood neurological disorders such as hyperactivity.

While exposure from a single receipt would be very low, she says the dose could add up as use of thermal paper is so ubiquitous.

The BPA that rubs off is quickly absorbed by the skin, getting to a depth where it can’t be washed off, she says.

BPA is part of the process that enables thermal paper to change colour when exposed to heat in credit card terminals, cash registers and ticket dispensers.

In 2010 Environment Canada added BPA to the list of toxic substances in Canada, and in 2012 asked industry to devise plans to reduce release of the substance into the environment.

Environment Canada said Monday it does not have any data on how much thermal paper containing BPA and BPS is used in Canada.

But as part of an voluntary control agreement, the “paper recycling sector agreed to initiate action to minimize the risk of existing environmental impacts from their effluent releases of BPA, where necessary, to the greatest extent practicable,” Danny Kingsberry, an Environment Canada media officer, said in written statement.

The latest data on BPA in Canada’s National Pollutant Release Inventory from 2013 “shows that 3.5 tonnes were sent for off-site disposal, 25 tonnes were transferred for recycling and .001 tonnes were on-site release into the air,” Kingsberry said. He said the department does not collect data on BPS.

Margaret's work covering science - and science controversies - has taken her to the Arctic to see the effects of global warming, to Cape Canaveral for space launches and into Ottawa's paper labyrinth ... read moreto reveal how the Canadian government has been muzzling scientists.View author's profile